Crown ether macrocycles can include cations into their cavity to form supramolecular cation (SC+) structures of various size, shape, and coordination environments.' We introduced the SC+ structures into highly conducting Ni(dmit)(2) (dmit = 2-thioxo-1,3-dithiol-4,5-dithiolate) salts as a countercation.? It was possible to exercise control the structure of SC+ the valence state, and the stacking mode of the Ni(dmit)(2) as well as the electrical conducting properties of the resultant salts For example, an ion-channel Lif(0.6)(+)(15-crown-5) structure was introduced into the crystal which has partially oxidized uniform Ni(dm,it)(2) stacks of metallic character.(3) The monovalent [Ni(dmit)(2)](-) with spin (S = 1/2) on each molecule may show a long-range magnetic order, provided an appropriate packing arrangement of [Ni(dmit)(2)](-) anions within the crystal. For example, a spin-ladder type magnetic chain has been reported in a [Ni(dmit)(2)](-) salt of pyridinium cation in which the large cation regulated the arrangement of [Ni(dmit)(2)](-) anions.(4) Control over the packing arrangements of [Ni(dmit)(2)](-) anions within the crystal should also be possible by utilizing a large structural diversity of SC+ units. Ln this paper, we describe the K+(DA 18-crown-6) [Ni(dmit)(2)] (1) and Rbf(DA18-crown-6)[Ni(dmit)(2)] (2) salts (DA18-crown-6 is 4,13-diaza-18-crown-6) in which the arrangement of [Ni(dmit)(2)](-) anions is regulated by the planar large SC+ unit to form a one-dimensional Heisenberg antiferromagnetic linear chain.